Tire inflators that seal and inflate to provide a temporary fix to a punctured tire are well known, they allow the driver of a vehicle to drive to a garage to have the tire repaired without fitting a spare tire. Developments have been made in order to address several issues to improve their performance and practicality. More specifically, tire inflators comprise a sealant composition and a source of pressurised gas, the pressurised gas serving to transfer sealant composition from a reservoir into a tire requiring repair and then serving to inflate the tire once sealant composition has to one extent or another sealed an aperture giving rise to a puncture. The source of pressurised gas can be derived from a mechanical compressor or it may be derived from an aerosol type canister in the form of a propellant. Prior art propellants include chlorofluorocarbons. However, since the manufacture of these have been phased out, as a result of their ozone depleting nature new propellants were required. Requirements for a suitable propellant include low vapor pressure (to avoid high pressures potentially resulting in tire over inflation or canister rupture), environmental acceptability, lack of flammability as well as the chemical and physical properties that allow the propellant to mix well with the tire sealant. WO 2011/133546 A2 provides a tire inflator with an environmentally acceptable propellant which is non-flammable at ambient conditions and has acceptable vapor pressure. Whilst issues relating to propellant have been widely explored the sealant composition compatible with environmentally acceptable propellants of known tire inflator systems is often nonoptimal. In particular, the usage of a relatively low vapour pressure propellant, for the reasons mentioned above, means that loss of gas can limit the durability of the repair as only a small amount of leakage is necessary for tire pressure to fall below acceptable levels. There is therefore a need for a tire inflator sealant composition which is compatible with an environmentally acceptable propellant and which gives improved puncture sealing, such as, as measured over time subsequent to a sealing operation being carried out.
In addition when a tire leak is occasioned by a puncture an issue arises where the puncture represents an aperture of significant size in a tyre. Apertures of up to 6 or even 10 mm in diameter can be occasioned when an object impinges upon a tyre, such as at high speed and tire sealant compositions particularly of a canister type are not currently available to repair such punctures. Large apertures realizes significant sealant propellant losses on tire repair when using a sealant composition and a significant loss of propellant and sealant can occur before a seal is realizable, if realizable at all.
Further to the problem of repairing a punctured tire in which the intention is typically to replace the tire at the earliest convenient opportunity, and hence the longevity of the sealing effect is less essential, it is becoming increasingly useful in situations where a poorly fitting tire or defective seating of a tire needs to be repaired and a permanent or semipermanent basis for intended ongoing use of the tire without replacement. This is particularly significant with so termed “alloy” wheel rims in which corrosion can give rise to poor sealing between a tubeless tire and the wheel rim. There is therefore a need for a tire sealant composition suitable for durable and effective permanent repair.